I love Dinobots, I decided to become a paleontologist 25 years ago, when I was 4 and I've received Snarl and Sludge for Christmas. So I definitely want to see at least one dinobot in the TF-movieverse.
I think Bay could easily introduce Grimlock, without confusing the plot, just thanks to Grimlock's temper.
I imagine Grimlock descending to Earth just near the Field Museum of Chicago which exhibits the largest mounted
Tyrannosaurus rex skeleton.
OP asks Grimlock for scanning a terrestrial vehicle, but Grimlock is always in competition with OP and doesn't take care of orders and disguise.. He only wants a strong alternate-mode which will permit him to rip off decepticon heads, and chooses
T. rex 
.
In my opinion the character design would fit better the tf-movieverse if based on the skeleton, instead of fleshed-out animal.
Two or three large autobots are needed, but not necessarily the dinobots. Take in your mind that without mass shift Snarl would be as large as a car (a 2 tons stegosaur) while Swoop (based on Pteranodon) would weighs as a child. Anyway, it would be nice to see the whole Dinobots team: Sludge (as large as Blackout/Grindor), Grimlock and Slag (both intermediate in height between OP and Ironhide), Snarl (Bumblebee sized), and Swoop (an agile and delicate spy..).
Also, Dinobots do not require a lot of screen time to be characterized psychologically, and they could result more faithful to their G1 counterpart than other characters introduced by Bay who would have needed more and more explanations.
Other large autobots could be Ultra Magnus (G1-like , a car-carrier truck with short-cab, rendering it shorter than Prime in the smaller robot mode but taller when combined with the trailer), and HotSpot or Inferno (I want to see a fire truck!).
and, on the autobot side, I'd like to see Hound (Jeep) and Wheeljack too(maybe an Italian car, such as the Lancia Delta - it could be possible after the Fiat-Chrysler joint venture).
